This section is about receivers that are made for intercepting communication
sent over wires, such as analogue telephone conversations. Such receivers are
commonly known as wire tapping devices. Tapping a telephone line is not
straightforward, as a device that is connected in parallel with the wiring
can usually be detected quite easily. As wire tapping is also known as
bugging, some of these device are also listed in our section about
covert listening devices (bugs).